From 62f488c24e346837168c9e106e0f80ab9559229a Mon Sep 17 00:00:00 2001
From: Max Bradbury <max@tinybird.info>
Date: Tue, 23 Jun 2020 16:36:33 +0100
Subject: [PATCH] sort and dedupe IDs

---
 src/lib.rs | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 1795a02..430fbfe 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -147,7 +147,10 @@ fn segments_from_string(string: String) -> Vec<String> {
 
 /// e.g. pass all tile IDs into this to get a new non-conflicting tile ID
 #[inline]
-fn new_unique_id(ids: Vec<String>) -> String {
+fn new_unique_id(mut ids: Vec<String>) -> String {
+    ids.sort();
+    ids.dedup();
+
     let mut new_id: u64 = 0;
 
     for id in ids {
@@ -237,8 +240,13 @@ mod test {
 
     #[test]
     fn test_new_unique_id() {
-        assert_eq!(new_unique_id(vec!["0".to_string(), "2".to_string()]), "1".to_string());
-        assert_eq!(new_unique_id(vec!["0".to_string(), "1".to_string()]), "2".to_string());
+        // start
         assert_eq!(new_unique_id(vec!["1".to_string(), "z".to_string()]), "0".to_string());
+        // middle
+        assert_eq!(new_unique_id(vec!["0".to_string(), "2".to_string()]), "1".to_string());
+        // end
+        assert_eq!(new_unique_id(vec!["0".to_string(), "1".to_string()]), "2".to_string());
+        // check deduplication
+        assert_eq!(new_unique_id(vec!["0".to_string(), "0".to_string()]), "1".to_string());
     }
 }